The invention relates to a vehicle having a bus system, which is designed as an Ethernet bus system and has at least one distributor device having a multiplicity of port connections, to which one bus participant respectively is connected. By way of the assigned port connection, during the operation of the bus system, the bus participant transmits data to the distributor device and/or receives data from the distributor device. In addition, the invention relates to a method of operating an Ethernet bus system in a vehicle.
Numerous bus system designs for motor vehicles are known from the state of the art. Today's motor vehicles are usually equipped with the so-called CAN (Controller Area Network) bus, which was developed specifically for the rapid serial data exchange between electronic control devices in motor vehicles. Furthermore, LIN (Local Interconnect Network) bus systems are also known, which also represent serial communication systems, but were developed specifically for more cost-effective communication of intelligent sensors and actuators in motor vehicles.
In the present case, an Ethernet bus system is of interest which can be used as an alternative or in addition to the CAN bus. The Ethernet bus system was at first used particularly for camera-based driver assistance systems. However, the newest trend aims at also mutually coupling other control devices and function features of a motor vehicle by way of an Ethernet network with respect to communication.
A bus system for a motor vehicle is known, for example, from International Patent Document WO 2008/095511 A1. The bus system includes several control devices as bus participants. For providing a bus system that is more flexible with respect to a fault diagnosis of the bus participants, it is suggested here that a gateway with an Ethernet interface be used, by way of which an external diagnostic device can be connected to the bus system. The gateway can be switched to a special diagnostic mode, in which—in contrast to the normal operating mode—under the control of the gateway, a bus message is transmitted to one of the bus participants, which corresponds to a message that this bus participant receives also during a regular operation of the motor vehicle. Although this permits a reliable and precise diagnosis of the bus participants, a special external diagnostic device will be required in this case. This state of the art therefore has a disadvantage in that the diagnosis can be carried out only in very specific situations, for example, only in a workshop.
It is an object of the invention to provide a method, as to how, in the case of a vehicle of the initially mentioned type, the expenditures of a diagnosis of the bus system can be reduced in comparison to the state of the art.
This and other objects are achieved by a vehicle as well as by a method in accordance with embodiments of the invention
A vehicle according to the invention, particularly a motor vehicle, comprises a bus system, which is designed as an Ethernet bus system and comprises as least one distributor device—such as a switch and/or a gateway—, which has a multiplicity of port connections, which represent the physical ports of the distributor device. One bus participant respectively is connected to the port connections. The bus participant, by way of the assigned port connection, during the operation of the bus system, transmits data to the distributor device and/or receives data from the distributor device. The at least one distributor device is designed for carrying out, during the operation of the bus system and therefore during the operation of the vehicle, a diagnosis with respect to at least one of the port connections and, in the process, providing diagnosis data with respect to the at least one port connection.
In contrast to the state of the art according to International Patent Document WO 2008/095511 A1, the diagnosis of the bus system according to the invention is not, or not only, carried out in a special diagnostic mode but rather during the normal or regular operation of the vehicle, during which regular application data between the distributor device, on the one hand, and the bus participants, on the other hand, are transmitted. In this case, the invention utilizes the fact that, in the case of an Ethernet bus system—in contrast to, for example, CAN buses or FlexRay buses—it is basically possible to create an “intelligent infrastructure” by the corresponding design of the distributor device. By way of the intelligent infrastructure, during the running time of the bus system, the exact network condition can be determined, faults can be located and predicted and, as required, can also be corrected. In order to be able to carry out the diagnosis, the distributor device may be equipped with corresponding software, which has no effect on the application level as well as on the bus participants themselves. The diagnosis can correspondingly be carried out in parallel and thereby in the background of the normal operation of the bus participants and of the distributor device. As a result, basically no external diagnostic devices are required, and the diagnostic data can be collected during the operation of the vehicle and, in this case, for example, stored in a central diagnostic memory.
The Ethernet bus system is represented by a LAN network of the vehicle, which permits the data exchange between the distributor device and the bus participants in the form of data frames or so-called data packets. The data exchange takes place according to the Ethernet protocol.
As indicated above, by means of the at least one distributor device, a diagnosis is carried out with respect to at least one of the port connections. In this context, different embodiments may be provided depending on which components of the bus system are in fact subjected to the diagnosis. On the one hand, the bus participant itself may be subjected to the diagnosis. On the other hand, it may also be provided that a data transmission channel between the distributor device and the bus participant is subjected to the diagnosis, i.e. the at least one port connection itself and/or an electric bus line coupling this port connection with the bus participant. As a function of the situation and according to the requirements, the diagnosis can therefore be carried out with respect to different components of the bus system.
Various embodiments may be provided also with respect to the distributor device.
In one embodiment, it is provided that the bus system comprises at least one control device of the vehicle as a distributor device, to whose port connections function components or function devices of the vehicle are connected as bus participants. Such a control device may, for example be a central control device (head unit) of the vehicle, which is used for triggering the various different function components, as for example, a navigation system, a display, a radio unit, an audio system, a telephone system and the like. However, a control device may also be a camera control device, which is used for triggering at least one camera of the vehicle and/or for processing image data of the camera. The at least one camera then represents a function component of the vehicle. In this embodiment, a diagnosis of function components of the vehicle is therefore permitted, particularly that of sensors and/or actuators.
In addition or as an alternative, it may be provided that the bus system comprises a central gateway as a distributor device, to whose port connections control devices of the vehicle are connected as bus participants. This embodiment, in turn, permits a diagnosis of the control devices themselves because here the central gateway takes over the function of a diagnostic device, by which a diagnosis can be carried out with respect to the control devices.
It was found to be particularly advantageous for the bus system to have a central evaluation device which is designed for storing and evaluating the diagnostic data. The at least one distributor device is then designed for transmitting the provided diagnostic data to the central evaluation device. The diagnostic data can thereby be centrally stored and evaluated in the evaluation device, which permits a monitoring of the diagnostic data for an extended period of time during the operation of the vehicle. By way of such a long-term “monitoring”, a prediction of faults in the bus system, for example, becomes possible. If faults are detected ahead of time, for example, corresponding fault reports can be emitted early and the faults can thereby be eliminated early.
The central evaluation device is preferably integrated in the central gateway. Because the bus participants—particularly the control devices and/or the function device—can always be reached by the central gateway directly, or indirectly by way of distributor devices or switches, or—as required—can also reach the gateway themselves, the central gateway can advantageously be used as the central evaluation device for evaluating and managing the diagnostic data. All diagnostic data are therefore known at the central point of the bus system and can therefore, for example, also be compared with one another.
It may also be provided that the central evaluation device has an interface, particularly an Ethernet interface, to which an external diagnostic device can be connected. By way of this interface, the diagnostic data and/or information obtained therefrom can be read out by the external diagnostic device. The communication with the external diagnostic device is therefore preferably limited to the transmitting of diagnostic data and/or of the information obtained therefrom, without requiring that an additional diagnosis be carried out by the diagnostic device itself.
With respect to carrying out the diagnosis by the at least one distributor device, the following embodiments may be provided.
Within the scope of carrying out the diagnosis, the at least one distributor device can examine the at least one port connection and/or a bus line connected to this port connection with respect to a physical fault, particularly an electric short circuit and/or an electric idling or an interruption. Such a fault can be recognized, for example, by a corresponding monitoring of a physical signal, such as an electric voltage at the port connection and/or of the electric current. Such a port-specific detection of physical faults ensures a secure operation of the bus system, because, in the event of a physical fault, the respective port connection can be actively switched off by the distributor device or be disconnected from a voltage source.
Within the scope of carrying out the diagnosis, the at least one distributor device can also determine the number of rejected data packets (data frames). Data that include information concerning the number of rejected data packets can then be provided as diagnostic data. The number of rejected data packets can be determined in the so-called MAC layer (media access control) of the distributor device and allows unambiguous conclusions concerning transmission faults of the data transmission channel between the distributor device and the respective bus participant.
As an alternative or in addition, within the scope of carrying out the diagnosis, the at least one distributor device can also determine a signal quality and/or a mean square error (MSE) of a physical signal at the at least one port connection, particularly of the voltage and/or of the current. In this case, the MSE is determined particularly from a gap between the expected signal level (voltage level) and the actually present signal level. On the basis of the MSE, the signal quality can be determined in turn. The determination of the signal quality and/or of the MSE also permits an unambiguous conclusion on the quality of the data transmission channel. Specifically, by use of the signal quality—assuming there is a defined interference, for example, a white noise—the so-called bit error rate can be determined, which represents a direct measurement of the quality of the data transmission channel. As a result, faulty or degraded bus lines and therefore an insufficient transmission quality can be detected. In addition, by monitoring the signal quality for an extended time period, it becomes possible to detect an aging or degrading bus line ahead of time within the scope of a forecast. If such a fault is detected ahead of time, a corresponding warning message can be issued by which the driver is informed early concerning a possible fault.
As mentioned above, it can be provided in an embodiment that the at least one distributor device determines a bit error rate as a function of the detected signal quality. Data that include information on the bit error rate can then be provided as diagnostic data. The bit error rate can thereby be monitored by way of the time.
As an alternative or in addition, data that include information concerning the signal quality and/or the MSE can also be provided as diagnostic data.
As a function of the signal quality, the at least one distributor device can also draw a conclusion concerning a technical state of the port connection and/or the bus line connected to this port connection. When, for example, insufficient signal quality is detected for a pre-determined duration, this directly indicates an insufficient technical state of the port connection and/or the bus line.
It can optionally also be provided in an embodiment that the diagnosis is carried out by means of the data (application data) received during the operation by the distributor device from the at least one bus participant. As required, application faults and thereby, for example, so-called “babbling idiots” can be detected. As a result, it in turn becomes possible to switch off those port connections to which such faulty bus participants are connected. These bus participants can thereby be disconnected from the remaining bus system in order to avoid an excessive bus load on the bus system.
Thus, within the scope of carrying out the diagnosis, a momentary bus load can be determined at the at least one port connection. The at least one distributor device may be designed to draw a conclusion, as a function of the momentary bus load, that there is an operating fault or an application fault of the bus participant connected to the port connection. When such a “babbling idiot” is detected, the assigned port connection can be switched off, the bus participant can be disconnected from the network, and the bus system can thereby be reliably protected.
On the whole, within the scope of the diagnosis, diagnostic data can be provided which describe the following faults:
Short-circuits and interruptions of the transmission line, i.e. physical bus faults,
insufficient transmission quality by faulty or degraded lines,
an aging or degrading line—these can be detected and also forecast,
frames rejected by MAC because of transmission faults,
changes in the network, i.e. lacking or newly added nodes, and/or
application faults by which an increased bus load is caused.
Furthermore, the effects of application faults on the network can be limited in that the data transmission of faulty nodes is stopped. In addition, the diagnostic functions generally have to be implemented in switch nodes, root nodes and regular application nodes. In this case, the essential diagnosis and fault treatment is limited to infrastructure components (root nodes and switch nodes) and therefore have no applicative influence.
Long-term monitoring and integrated supervision of the network utilization in the service life cycle of the vehicle can therefore be carried out for the first time. Switch-off scenarios and fault corrections can be implemented on this basis. For example, the faulty “sick” part of the vehicle can thereby be cleared away. In addition, for the first time, a forecasting of degrading components (wire harness) can take place for the first time by way of a long-term monitoring of CRC errors and of the signal quality.
A method according to the invention is used for operating an Ethernet bus system in a vehicle, whereby at least one distributor device communicates with a multiplicity of bus participants, which are connected to respective port connections of the distributor device and, by way of the respectively assigned port connection, during the operation of the bus system, transmit data to the distributor device and/or receive data from the distributor device. By way of the at least one distributor device, a diagnosis with respect to at least one of the port connections is carried out during the operation of the bus system, and in the process, diagnostic data are provided with respect to the at least one port connection.
The preferred embodiments and their advantages introduced with respect to the vehicle according to the invention correspondingly apply to the method according to the invention.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawing.